1. Field of the Invention
This invention relates to an apparatus for sealing conduits and more particularly, to an axially insertable, easily removable valve or plug which is operable to seal a conduit, thereby blocking fluid flow therefrom.
2. Description of the Prior Art
In the past, there have been applications in which it has been desirable to provide an insertable sealing member for a conduit, which is independent of any closure of the conduit. This is especially so in situations involving conduits having diameters of approximately 10 cm or greater where a cap or other closure device would tend to be large and bulky, especially if such conduits require quick sealing and/or removal to enable the conduit to be utilized.
A typical application for the present invention is in the drain conduit of an accumulating type tank, such as is found on aircraft. Typically, aircraft lavatory and toilet facilities drain into a large holding tank which must be periodically flushed and/or drained during the ground servicing of the aircraft. This requires that the conduit be quickly and easily opened and closed.
The assignee of the present invention has, through its predecessors in interest, manufactured and sold complete coupling assemblies adapted for temporary connection to such a tank or conduit outlet. Such coupling assemblies are used for quickly and efficiently draining the waste tank of an aircraft. A special plug was designed that could be remotely installed and removed in conjunction with the assembly.
That assembly and drain plug is disclosed in the U.S. Pat. to William B. Lynch, No. 3,010,694. A quick connect drain member is shown in FIGS. 1-4, inclusive and a conduit plug is disclosed and shown in FIGS. 5-8. The present invention is deemed a replacement of and substitute for the plug that was disclosed and claimed in that patent.
According to the Lynch patent, and as described in column 3, lines 21 et seq., a torus of elastomeric material, for example, a silicon rubber, is flattened and a second ring of a second material, such as sponge rubber separates the walls of the flattened torus.
A rigid material, such as steel, is used for the top and bottom cover plates. A cam mechanism is provided to extend and retract the cover plates in the axial direction to thereby compress the elastomeric sealing member. Applying a compressive force over substantially all of the area of the torus caused it to extrude in the radial direction, thereby sealing a conduit whose diameter closely approximated that of the plate members.
Because of the large volume of the elastic sealing member that had to be compressed, and because all of the operating cam mechanism, was located on the interior axis of the plug, the upper and lower plates had to be capable of transmitting substantially all of the compressive forces without deformation.
Further, from an examination of the plug structure, as disclosed in the Lynch patent, the plug required the assembly of many parts into a relatively complex structure that, among other things, did not permit easy replacement of the sealing member. The use of plastic materials enables mass production economies as well as a simplification of the assembly process.
It was therefore desirable to have a sealing plug of simpler and less costly construction and of lighter weight. Further, it was desirable to have the sealing member easily replaceable so that the same plug body might be utilized on conduits having different interior wall textures and with limited size variations.